This invention relates to a circuit board which is capable of serving the purpose of a wire harness for an automobile. More particularly, the invention relates to a circuit board to replace at least part of a wire harness composed of a plurality of bundled wires, said wire harness having a design corresponding to a predetermined wiring pattern in an automobile structure so that the space occupied by the wire harness is reduced, the wiring thereof may be made with ease, and productivity may be increased.
A conventional wire harness is formed by determining the wiring path thereof in advance, and tying the electric wires into a bundle. One such example is shown in FIG. 19, wherein a denotes an electric wire, b denotes a vinyl tape, and c denotes a connector. A wire harness A has a plurality of subharnesses e branching from a main harness d. In this way, it has a complicated construction. FIG. 20 shows the placement of wiring harness A in an automobile B wherein the harness A is arranged along a predetermined wiring path, so that it lies along portions of various constructions, shapes, etc. in the automobile B, and fixed to a vehicle body by clips, clamps, etc. (not shown).
Prior wire harness have become bulkier and bulkier due to ever increasing numbers of eletronic parts to be mounted on an automobile. Moreover, due to the space requirements of the electric items themselves, the wire harness often interferes with various parts and the vehicle body, which makes it difficult to obtain a sufficient space for wiring. Furthermore, as the wire harness becomes larger and its weight increases, difficulties in the manufacturing process, mounting process, etc. are increased, resulting in the following problems.
(1) Electric wires constituting a wire harness have many different diameters and lengths, and branching electric wires for connecting auxiliaries originate from various points on the main harness. Accordingly, working processes are increased and automation is difficult to obtain.
(2) Different wire harnesses are required to be made according to different specifications and grades of an automobile, even if its type and model are same. Accordingly, they are extremely complicated to manufacture and to control.
(3) When electric wires are joined together, such additional tasks as peeling off the insulation, pressure welding of joint terminals, and wrapping of insulated tapes to joint portions are required. Furthermore, the joint portions are enlarged due to the above mentioned terminals, insulated tapes, etc. Accordingly, the shape of the wire harness becomes irregular.
(4) There is a tendency that wire harnesses are made even larger according to increase of the number of circuits. Accordingly, if the wire harnesses should remain in their present form, their wiring would become more and more difficult, which eventually results in a reduced space in an automobile.
The present invention solves the above mentioned problems inherent in the prior art. In particular, the enlarged portions of the wire harness, for example, the portion where electric wires are concentrated (main harness d in FIG. 19) and branch points (sub-harness in FIG. 19), are made flat just like a usual printed circuit board (P.C.B) and a flexible printed circuit board (F.P.C).